Question

我在停靠小部件中有一个可编辑的列表视图。我希望在用户编辑之前跟踪数据，并在用户编辑之后保留数据。完整的相关代码是：

void MainWindow :: createDock()
{
    //initialize dockWidget
    QDockWidget *dock = new QDockWidget("Tags", this);
    dock->setAllowedAreas(Qt::LeftDockWidgetArea | Qt::RightDockWidgetArea);
    dock->setFeatures(QDockWidget::DockWidgetFloatable | QDockWidget::DockWidgetMovable);

//widget to store all widgets placed inside dock because dock cannot set layout but can set widget
QWidget *tags = new QWidget(dock);

//initiazlize treeViewModel
listViewModel = new QSqlTableModel(this);
listViewModel->setTable("tags");
listViewModel->select();
listViewModel->setHeaderData(0, Qt::Horizontal, "Tags");

//set the model for treeView
listView = new QListView(dock);
listView->setModel(listViewModel);

connect(listView, &QListView::doubleClicked, this, &MainWindow::onListViewDoubleClicked, Qt::UniqueConnection);
connect(listViewModel, &QSqlTableModel::dataChanged, this, &MainWindow::onLVDataChanged, Qt::UniqueConnection);

//add treeView to the dock
QVBoxLayout *layout = new QVBoxLayout;
layout->addWidget(listView);
tags->setLayout(layout);

//add the dock widget to the main window and show it
dock->setWidget(tags);
this->addDockWidget(Qt::LeftDockWidgetArea, dock);
//dock->show();
}

void MainWindow :: onLVDataChanged(const QModelIndex& index, const QModelIndex& index2, const QVector<int> & roles)
{
    QMetaMethod metaMethod = sender()->metaObject()->method(senderSignalIndex());
    QMessageBox::information(this, "", metaMethod.name());

afterUpdate = index.data().toString();

//do somethings

beforeUpdate = "";
afterUpdate = "";
}

void MainWindow :: onListViewDoubleClicked(const QModelIndex &index)
{
    QMetaMethod metaMethod = sender()->metaObject()->method(senderSignalIndex());
    QMessageBox::information(this, "", metaMethod.name());

beforeUpdate = index.data().toString();
}

我这样做：我双击一个项目以进行编辑。 onDoubleClick（）只被调用一次（因为QMessageBox）。我为存在的数据添加了一个空格（在我的例子中，它是“虚构的”，我将其改为“小说”）。但是，按下回车后，dataChanged（）被调用两次（再次通过QMessageBox看到）。

我没有明确发出信号。它仅由模型发出。

Answer 1

问题是由编辑策略引起的，默认情况下是QSqlTableModel::OnRowChange，这需要更改行，发出信号以更新项目，另一行更新整行，这很容易看出我们使用以下内容：

void MainWindow::onListViewDoubleClicked(const QModelIndex &index)
{
    qDebug()<<__FUNCTION__<<index;
}

void MainWindow::onLVDataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles)
{
    qDebug()<<__FUNCTION__<<topLeft<<bottomRight<<roles<<topLeft.data();
}

输出：

onListViewDoubleClicked QModelIndex(1,0,0x0,QSqlTableModel(0x562940043670))
onLVDataChanged QModelIndex(1,0,0x0,QSqlTableModel(0x562940043670)) QModelIndex(1,0,0x0,QSqlTableModel(0x562940043670)) QVector() QVariant(QString, "tag2 ")
onLVDataChanged QModelIndex(1,0,0x0,QSqlTableModel(0x562940043670)) QModelIndex(1,2,0x0,QSqlTableModel(0x562940043670)) QVector() QVariant(QString, "tag2 ")

解决方案是将编辑策略更改为QSqlTableModel::OnManualSubmit：

...
listViewModel = new QSqlTableModel(this);
listViewModel->setTable("tags");
listViewModel->setEditStrategy(QSqlTableModel::OnManualSubmit); // <--
listViewModel->select();
listViewModel->setHeaderData(0, Qt::Horizontal, "Tags");
...

插槽叫qt两次

1 个答案: